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Trying to figure out why my brakes are minimal all of the sudden So far, the only leak I have found is in this location and not sure what the part is called. Brake fluid is apparently disappearing because I had to fill the master up yesterday
What you have your finger on is the axle vent tube nipple. The should be some hose attached to it running above the axle. I zip tied mine to the shock. The nipple should be clear of dirt/mud etc.
If not it can cause the pressure inside the axle to spew gear oil out of axle seals at the ends.
it also attaches the rear brake line splitter (?)
Unscrew it make sure it is clean on the inside. The fittings from the brake lines that attach to either side could be leaking. I would clean it all up before removal and then check everything.
The part you have your finger on is as John89 said, the part under it is a distribution block the rubber line feeds brake fluid to each of the rear brakes.
Yes it is a duel purpose block. 1. It takes break fluid from the rubber line coming down from the frame and puts it into the T and that splits it to the L&R wheel cylinder. 2. The T block is mounted to the axle with a threaded hollow bolt. That is your axle vent function. And yes there is a metal cap that should not be on there. It should have a open end rubber hose going up to the frame rail, to let the axle vent pressure. You cap it and you can get axle seal leaks.
Maybe but that metal cap sits there loosely. Keeps debris and water out. The cap should be pretty loose and should move if you twist it.
review post #4 and #5. Best plan of attack, start at the top and work your way down. Its going somewhere and probably not at that block but, if you have a helper, have them pump while you look
pull each wheel and see if the calipers and wheel cylinders are leaking. Just went through this myself. Also, unbolt the master cylinder from the booster and see if there’s moisture there.
This is what the typical breather-bolt that everyone is talking about looks like: https://www.wildhorses4x4.com/produc...co_Brake_Hoses
A hose runs from it up to the frame usually and is clamped in place. Most I've seen on Fords were open ended, but protected from direct incursion by the frame rail. Many other manufacturers, and probably Ford too by now, use a capped insert in the end that would be similar to the one on your axle. Or a plastic version thereof.
Yours is fine if your truck never goes off-road or into the snow. But it's too low to keep water out if you get in deeper than axle height. Which is why Ford put it up high originally anyway. Some vehicles like older Toyota trucks had this type of vent but mounted down low too. Nice vent, but not good for off-roading.
But if you live where mud and/or snow and/or creek crossings are something that might happen now and then, raising the vent back up to the frame level (or higher) would be a good thing.
And if you have yours out for whatever reason, perhaps to change the brake hose assembly out, verify that the hole into the axle housing is free and clear. Lots of them get a buildup over time and stop venting, which can cause a gear lube leak out the axle seals.
When I first got my truck , I pulled the brake booster off and found a pint or more of brake fluid inside of it ,,look under the master cylinder to see if its seeping on booster ,
I don't know if you know this, so I am going to say it anyway. Just because you think you have to add fluid doesn't necessarily mean you have a leak. As your brake shoes and pads wear down during normal use, the caliper pistons and wheel cylinders will retract less and less as the shoes and pads wear down. This causes your brake fluid to go down (this is why there is a rubber boot in your MC lid). In this situation, do not add fluid. When you replace your shoes and pads, your fluid will go back up because the caliper piston and wheel cylinders will be fully retracted. If you added fluid, it will over fill the master cylinder. Hopefully I didn't insult you.
As for the axle vent, pretty good feeling that is axle grease leaking from there and not brake fluid. I would get the right hollow bolt with nipple to replace yours and use a three foot rubber tube and ziptie the other end up to the frame. I ziptied an inline gas filter to the top of mine so nothing big clogs it.
Check your brake shoes and pads. If worn to less than three millimeters of pad left on the metal plates, time to replace.
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